[Effect of nitric oxide on central dopaminergic neurons]

Neuronal damage induced by ischemia involves various changes in neurotransmission. Nitric oxide (NO), a putative neurotransmitter and/or neuromodulator has some role in this neuronal damage. In the present study, the effect of NO on the terminal site of dopamine (DA) neurons in the rat striatum was examined using the microdialysis technique. First perfusion with sodium nitroprusside (SNP) as an NO donor increased extracellular DA (10 mM, 460%; 1 mM, 140%) in the striatum and decreased its metabolites. Pretreatment with tetrodotoxin (TTX, 5 microM), (+)-5-methyl-10,11-dihydro-5H-dibenzo [a,d] cyclohepten-5,10-imine hydrogen maleato (MK801, 1 microM) or muscimol (1 microM) inhibited SNP-induced increases in extracellular DA and decreases in DOPAC (TTX, complete block; MK801, 75% inhibition; muscimol, 80% inhibition). Second, extracellular NO, DA and DOPAC were measured in the gerbil striatum following 10 minutes of forebrain ischemia produced by occluding both carotid arteries. Occlusion of the carotid arteries also caused increases in extracellular NO and DA in the gerbil striatum (NO, 3000%; DA, 2800%). These findings suggest that NO-facilitated DA release occurs via interaction between glutamatergic and dopaminergic neurons. These changes are probably partially involved in the neurodegenerative phenomena following ischemia. It is also shown that simultaneous measurements of NO and DA using this technique may be useful in assessing ischemic changes in vivo.

[A resected case of esophageal leiomyoma with 15 cm in long diameter, diagnosed by transesophageal ultrasonic endoscopy]

A 28-year-old man whose chest X-ray film showed a mass on the right upper mediastinum was admitted. Preoperative examination, including CT, MRI, esophagogram, did not make it possible to determine clinically from which organ the tumor originated. On diagnosing with transesophageal ultrasonic endoscopy (TUE) the tumor was found to originate in the esophageal submucosa, with no involvement of the mediastinal organ apparent. Esophageal sub-mucosal tumor enucleation was performed. The resected tumor was 15 cm in long diameter and weighed 125 g. We therefore believe that TUE is clinically useful in diagnosing the tumor originating in the esophageal wall or adjoining esophageal wall.

Levoglucosan dehydrogenase involved in the assimilation of levoglucosan in Arthrobacter sp. I-552

A levoglucosan (1,6-anhydro-beta-D-glucopyranose)-using bacterium, isolated from soil, was identified. It was shown to belong to the genus Arthrobacter and tentatively named Arthrobacter sp. I-552. A novel enzyme catalyzed the dehydrogenation of levoglucosan to form 1,6-anhydro-beta-D-ribo-hexopyranos-3-ulose (3-keto levoglucosan), using NAD+ as an electron acceptor, i.e. NAD+: 1,6-anhydro-beta-D-glucopyranose oxidoreductase (trivial name: levoglucosan dehydrogenase). This enzyme was purified and characterized. A possible reaction scheme for the glucose formation was proposed. This pathway for levoglucosan use is distinct from those in yeast and fungi.

FR901451, a novel inhibitor of human leukocyte elastase from Flexibacter sp. II. Pharmacological effect of FR901451

Intratracheal (i.t.) or intravenous (i.v.) administration of FR901451, a potent inhibitor of human leukocyte elastase (HLE) prevented HLE-induced lung hemorrhage in hamsters with ED50 values of 10.5 micrograms/site and 8.1 mg/kg, respectively. alpha 1-Antitrypsin (alpha 1-AT) also showed inhibitory effect in this model. However, the ED50 value by i.t. injection of FR901451 was 20-fold lower than that of alpha 1-AT. Moreover, FR901451 i.t. significantly modulated porcine pancreas elastase (PPE)-induced changes of the respiratory mechanics in hamsters. The ED50 values were 529 micrograms/site and 244 micrograms/site, which were expressed by static lung compliance (Cst) and vital capacity (VC) of the lungs, respectively. These results suggest that FR901451 could be clinically useful agent for the treatment of the destructive lung disease such as pulmonary emphysema.

[Two cases of distal superior cerebellar artery aneurysm]

Two cases of subarachnoid hemorrhage due to a ruptured aneurysm of the distal superior cerebellar artery (SCA) are reported. In the first case the patient was a 78-year-old woman who complained of severe headaches and was admitted to a local hospital on May 25, 1992. A CT scan revealed a subarachnoid hemorrhage, and an angiogram showed an aneurysm of the right ambient segment of the superior cerebellar artery. Trapping of the aneurysm was successfully performed via a subtemporal approach on June 9, 1992. In the second case the patient was a 46-year-old man who complained of severe headaches and was admitted to Kurume University Hospital. A CT scan showed subarachnoid hemorrhage and an angiogram showed an aneurysm of the right ambient segment of superior cerebellar artery. Trapping of the aneurysm was successfully performed via a subtemporal approach on Sept 11, 1990. Forty-three reported cases of distal SCA aneurysm were reviewed. Only one patient received early surgical treatment, and with surgery in all of the other cases being delayed. Both of our patients underwent delayed surgical treatment with excellent results. The clinical characteristics of distal SCA aneurysms and the timing of surgery are discussed.

Genetic linkage analyses of Romano-Ward syndrome (RWS) in 13 Japanese families

Romano-Ward syndrome (RWS) is an autosomal dominant disorder characterized by prolongation of the electrocardiographic QT interval, with clinical manifestations that include recurrent syncope and sudden death from ventricular arrhythmias. Presymptomatic diagnosis is difficult because of the variability in these signs among carriers, but it is important for clinical management to prevent sudden cardiac death. To find an LQT (long QT) locus in Japanese patients and to identify DNA markers useful for presymptomatic diagnosis, linkage analyses were undertaken in 13 Japanese families with RWS patients by means of two DNA markers located on 11p15.5. One of these marker loci, HRAS, was previously reported to be tightly linked to the LQT locus in another ethnic group. Our analyses of homogeneity suggest evidence for genetic heterogeneity of RWS within the Japanese population.

GLUT2 expression in the rat retina: localization at the apical ends of Müller cells

In order to understand the molecular basis of glucose regulation supporting visual function, this study examined the presence of GLUT2, a facilitated-diffusion glucose transporter isoform, and delineated its localization in the rat retina. Reverse transcriptase-polymerase chain reaction (RT-PCR) demonstrated the presence of GLUT2 mRNA, and immunoblot analysis using polyclonal antibody specific to rat GLUT2 revealed a band at a molecular weight of approximately 60 kDa, indicating the presence of GLUT2 protein in the rat retina. Fluorescence and electron microscopy localized GLUT2 expression to the apical ends of Müller cells that face the inter-photoreceptor space. These findings suggest that GLUT2 on Müller cells may control intra-retinal glucose homeostasis by performing both anterior and posterior glucose transport within the rat retina. This is the first study to provide evidence that GLUT2 is present in the mammalian central nervous system and indicates that GLUT2 may have local glucose homeostatic functions within the retina in addition to its role in the regulation of systemic blood glucose level.

Cytosolic Ca2+ increase and cell damage in L6 rat myoblasts by HMG-CoA reductase inhibitors

Acute rhabdomyolysis is caused by HMG-CoA reductase (HCR) inhibitors clinically and experimentally. To study the mechanism of muscle cell damage, we investigated the change in the cytosolic free Ca2+ concentration ([Ca2+]i) in L6 rat myoblasts stimulated with three kinds of HCR inhibitors: simvastatin, simvastatin-acid form and pravastatin. Simvastatin and simvastatin-acid form induced an increase in [Ca2+]i through two different pathways, namely, the Ca2+ release from intracellular stores and the Ca2+ influx from extracellular solution. They also caused cell puncture either in the presence or absence of extracellular Ca2+. Pravastatin induced little or no change in [Ca2+]i and no cell damage resulted. Simvastatin was 10-fold more potent than simvastatin-acid form. These results suggest that the mechanism of cell damage may relate to the [Ca2+]i elevation by these drugs and may be dependent on the lipophilicity of the inhibitors.

Suppression of lymphocyte spontaneous proliferative response by proteolipid protein peptide in patients with HAM/TSP

To understand the immune mechanism suggested in HTLV-I-associated myelopathy (HAM/TSP), we investigated T cell response to proteolipid protein (PLP). Because of high autologous proliferative response (APR) of peripheral blood mononuclear cells (PBMC) in culture, the lymphocyte proliferation assay was not useful in this disease. Unexpectedly, however, APR was profoundly (70-98%) suppressed in 6 of 9 cases when PLP peptide 105-124 was added in the culture. PLP peptide 85-104 or 145-159 also suppressed APR in a few cases. Time course study showed that the peptide-mediated suppression became apparent after day 4 in culture. The results can be interpreted as that suppressor cells recognizing the PLP peptides were present in the PBMC of HAM/TSP patients and suppressed the APR as the consequence of antigen specific response. This may indicate that a T cell response to certain PLP determinants is involved in the pathomechanism of HAM/TSP at least in part. Molecular mimicry between PLP and HTLV-I may account for the T cell sensitization to PLP in HAM/TSP.

Electrical myotonia of rabbit skeletal muscles by HMG-CoA reductase inhibitors

HMG-CoA reductase (HCR) inhibitors are effective cholesterol-lowering agents in the treatment of hypercholesterolemia. Using intracellular microelectrodes, we studied the pathomechanism of myotonia experimentally induced in rabbits by HCR inhibitors, simvastatin, and pravastatin. The external intercostal muscle of rabbits showed some electrophysiologic characteristics of myotonia including repetitive firing after administration of simvastatin (50 mg/kg per day, for 4 weeks). The relative chloride conductance, though reduced in both, was more affected in simvastatin-administered muscles. In normal muscles perfused with a solution containing the inhibitors, both simvastatin and pravastatin produced membrane hyperexcitability with repetitive firing similar to that seen in simvastatin-administered rabbits. The minimum concentrations required to cause repetitive firing was 0.3 mg/L for simvastatin and 30 mg/L for pravastatin. These results indicate that HCR inhibitors induce some characteristics of myotonia by blocking the chloride channel in the muscle membrane.

Kinetics and thermodynamics of CO binding to cytochrome P450nor

The CO-binding reaction of cytochrome P450nor isolated from denitrifying fungus, Fusarium oxysporum, has been studied by using a flash photolysis method in the millisecond time domain. We obtained the CO on- and off-rate constants in the bimolecular reaction, and determined the activation free energy, enthalpy, and entropy from the temperature dependence of these rate constants. To discuss the structural characteristics of P450nor, these parameters were compared with those of other cytochrome P450s, such as cytochrome P450cam from Pseudomonas putida and myoglobin. The on-rate constant (k(on)) for P450nor is larger than those of camphor-bound P450cam [P450cam(+)], suggesting that ligand entry to the heme pocket of P450nor is sterically less restricted than that of P450cam(+). In the P450norCO complex, the IR stretching band of the iron-bound CO is observed at 1942 cm-1, which is the same position as in P450cam(+)CO. This result suggests that the heme pocket immediate to the ligand-binding site is the same size in the two enzymes, in good agreement with the observation that the equilibrium constant (K = k(on)/k(off)) is identical in P450nor and P450cam(+). On the other hand, the entropy changes in the equilibrium and the off-activation processes are smaller in P450nor than in P450cam(+). This feature could reflect the lack of a bound substrate at the active site of P450nor. These structural characteristics of P450nor are discussed in relation to its unique catalytic property, rapid NO reduction to yield N2O.

Effect of FR128998, a novel PAF receptor antagonist, on endotoxin-induced disseminated intravascular coagulation

This study aimed to evaluate the effect of FR128998, (1s,6s)-1-benzyl-10-(3-pyridyl-methyl)-7-thia-10-azaspiro [5,6]-dodecan-11-one 7,7-dioxide hydrochloride, a novel platelet activating factor (PAF) receptor antagonist, on endotoxin lipopolysaccharide-induced disseminated intravascular coagulation in rats. Experimental disseminated intravascular coagulation was induced by an infusion of lipopolysaccharide at 0.25 mg/kg/h for 4 h. Simultaneous infusion of FR128998 (0.25 and 1.0 mg/kg/h) with lipopolysaccharide dose dependently inhibited thrombocytopenia, but not leukopenia. The changes in coagulation parameters of disseminated intravascular coagulation, i.e., prolongation of activated partial thromboplastin time and elevated levels of fibrinogen/fibrin degradation products, were also prevented by the treatment with FR128998. In addition, FR128998 attenuated the increase in serum tumor necrosis factor (TNF) which appeared during the initial stage of disseminated intravascular coagulation. FR128998 (10 microM) also inhibited the TNF production by peripheral blood leukocytes or alveolar macrophages stimulated by lipopolysaccharide in vitro. Furthermore, TNF production induced by PAF itself in vitro was also inhibited in the presence of FR128998. These data indicate that PAF plays a pivotal role in the development of disseminated intravascular coagulation via TNF production.

Elevated soluble CD4 levels in the cerebrospinal fluid in patients with adult T-cell leukemia

Levels of the soluble form of the leukocyte surface antigen CD4 (sCD4) were measured by enzyme linked immunosorbent assay (ELISA) in the cerebrospinal fluid (CSF) of patients with adult T-cell leukemia (ATL) and other malignant and non-malignant diseases. All patients with ATL and meningeal infiltration had markedly elevated levels of sCD4 in the CSF (53.7 +/- 34.9 U/ml). ATL patients without CSF pleocytosis often had elevated levels of sCD4 (15.1 +/- 9.2 U/ml). Non-ATL patients with CSF pleocytosis had elevated levels of sCD4 (23.3 +/- 12.2 U/ml) and those without CSF pleocytosis also showed elevation of sCD4 levels (16.8 +/- 9.3 U/ml). However, the mean levels of sCD4 in CSF from these patients were significantly lower than ATL patients with meningeal infiltration. Soluble CD4 in the CSF from healthy volunteers were below the detectable limit. We conclude that meningeal infiltration of CD4(+) ATL cells is strongly associated with elevated sCD4 levels in CSF, and some part of sCD4 in CSF may be originated from the native cells in the CNS as a response of inflammatory stimulations. Therefore, measurement of sCD4 may be useful in the diagnosis of meningeal infiltration and/or meningeal irritation in patients with ATL.

Crystallization and preliminary X-ray diffraction studies of nitric oxide reductase cytochrome P450nor from Fusarium oxysporum

Crystals of cytochrome P450nor (P450nor), nitric oxide reductase from Fusarium oxysporum, were obtained by means of the hanging-drop vapour diffusion technique in the presence of 1.88 M ammonium sulphate (pH 7.2). They belong to the monoclinic space group P2(1), with unit cell dimensions of a = 74.7 A, b = 86.7 A, c = 62.0 A and beta = 97 degrees. There are two molecules of P450nor in the asymmetric unit. The crystal diffracted to beyond 2.5 A resolution and is suitable for X-ray crystallographic study.

Bcl-2 expression in the thymus and periphery

Bcl-2 proto-oncogene is expressed in normal lymphoid tissues and its role has been suggested to involve the selection of B and T cells. Here we report three-color flow cytometric studies on the expression of bcl-2 protein in the thymus and periphery. Bcl-2 was expressed in the majority of T and B cells and down-regulated only in the CD1+, CD3- to low, CD4+8+ thymocytes, and the B cells that are in cell cycle in the tonsil and lymph node. In contrast, the CD2+, CD1-3-4-8-19-, early T cells, and mature single positive cells in the thymus, as well as the tonsilar and lymph node T cells, irrespective of their cell cycle status, expressed bcl-2. These results are consistent with the notion that bcl-2 is down-regulated in the T and B cells that are in the process of generating new antigen receptors and subject to subsequent positive selection.

[The effect of cocaine on uterine contractions in the rat]

The abuse of cocaine during pregnancy has become a major problem in substance abuse in the U.S.A. Although cocaine often induces preterm labor, little is known about the effect of this drug on uterine contractions. In 23 pregnant (P) and 23 nonpregnant (NP) rats, a carotid artery and jugular vein were catheterized, and a balloon catheter was inserted into the uterine cavity 24 hrs prior to the study. Arterial blood pressure, heart rate, intrauterine pressure were recorded throughout the study. Uterine contractions were expressed in Montevideo Units (M.V.U.). Cocaine (1.25-20 mg/kg) or saline was administered intravenously to test its toxicity and the effect on uterine contractions. A 1.25 or 2.5 mg/kg dose of cocaine did not produce toxic symptoms, but 2.5 mg/kg resulted in a marked increase in M.V.U. in both P and NP. In P, the maximum change in M.V.U. was as high as 250% from the baseline value, twice as much as that observed in NP. Mean arterial blood pressure increased 15% on the average and heart rate decreased 10%. This study indicates that a non-toxic dosage of cocaine stimulates uterine contractions, and pregnancy enhances this effect.

Nuclear proteins binding to a novel target sequence within the recombination hotspot regions of Bcl-2 and the immunoglobulin DH gene family

The chromosomal breakpoints of follicular lymphomas carrying the t(14;18)(q32;q21) are known to be clustered within a 150-bp region in the major breakpoint region (mbr) of the Bcl-2 oncogene. We have demonstrated that nuclear proteins specifically bind to a novel target sequence within this 150-bp region and a region of Dxp genes, members of the immunoglobulin (Ig) diversity (DH) gene family. One protein, designated BCLF-1, appears to be specifically expressed in lymphoid lineage cells. Two other proteins, BCLF-2 and -3, bind only to the complementary single strand of the target sequence. The manner in which these proteins interact with the target sequence is similar to the interaction of the ReHF-1 and -2 proteins to the signal-like sequence at the chromosomal breakpoint junctions in patients with the t(8;14)(q24;q11) and t(1;14)(p32;q11) translocations. It was further suggested that the BCLF-1 is quite similar to or identical to the ReHF-1. It is therefore hypothesized that these conserved target sequences found in recombination hotspot regions may define novel sequence motifs recognized by two classes of DNA binding proteins. One class of DNA binding proteins is specifically expressed in lymphoid cells while the other class binds to the complementary single strand DNA. These binding activities may play a crucial role in chromosomal translocation in lymphoid neoplasms.

[A case of primitive neuroectodermal tumor in the chest wall ("Askin's tumor")]

We report a case of Askin's tumor, primitive neuroectodermal tumor (PNET) in the chest wall, with review of reported cases of PNET. Our case was the ninth of Askin's tumor and the 36th of PNET in Japan. A 12-year-old girl was hospitalized because of a large right intrathoracic mass. The serum neuron-specific enolase (NSE) was 11.4 ng/ml, slightly increased, and the urinary excretion of catecholamine metabolites was normal. The needle biopsy specimens were diagnosed as small round cell sarcoma. At surgery we found an encapsulated multilobular mass in the region. The chest wall was resected partially to extirpate it completely. Its macroscopic and microscopic features were almost similar to the description of Askin et al. The immunohistochemical staining of the cells was positive for NSE, strongly suggesting the neurogenic origin. After surgery, intensive chemotherapy with autologous bone marrow transplant was performed, and she has been living without sign of recurrence for two years.

Mediastinal ultrasonography for the assessment of mediastinal lymph node metastases in lung cancer patients

Using an ultrasonic probe inserted into the mediastinum during cervical mediastinoscopy, mediastinal ultrasonography (USM) was performed on 63 patients with lung cancer. The patients with a small peripheral mass of less than 2 cm in diameter, according to the chest X-ray results, and with mediastinal lymph nodes smaller than 1 cm in their short axes as determined by computed tomography (CT), were excluded from this study. An analysis of the areas under the receiver operating characteristic curves derived from CT and USM showed that USM was superior (P = 0.043) to CT in terms of the diagnosis for mediastinal lymph node metastases, when the short axis dimension of mediastinal lymph nodes was employed for the diagnosis of metastases. The reason for this is that 97% of the mediastinal lymph nodes imaged by USM were located vertically along the body axis of the patient, and hence USM imaged the true short axis of the node in many cases. Our results indicate that USM is useful for performing a safe biopsy of lymph nodes during mediastinoscopy as well as for obtaining a clear imaging of the subcarinal nodes, which are inaccessible by normal cervical mediastinoscopy.

[Role of malnutrition on immunity]

Although the relationship between starvation and reduced resistance to infection has been suggested by historical accounts of famines and pestilence and by recent epidemiologic studies, the concept of nutritional deficiency causing impairment of immunocompetence is relatively recent. In PEM (protein-energy malnutrition), most of the host defence mechanisms are breached, especially manifested in reduced cell-mediated immunity. One plausible reason is the reduction in mature fully differentiated T lymphocytes. Recent immunological methods made it possible to analyze its precise mechanism and process in detail. Naturally occurring states of malnutrition are difficult to interpret largely because deficiencies usually involve multiple dietary factors. It is obvious that single nutrients can only be analyzed in defined and controlled animal experiments. Role of micronutrients such as zinc, iron, and vitamins, specific amino acids such as arginine, glutamine, and fat on immunological responses have been paid attention on their specific actions and some of them have been investigated in humans as well.

Effect of omentopexy on wound healing of the extensively detached and anastomosed canine trachea

BACKGROUND

To examine the beneficial effect of omentopexy for tracheal anastomosis after extensive detachment that may cause impairment of the blood supply, the time course of tracheal wound healing was studied experimentally.

METHODS

Circumferential resection of the trachea for three cartilage rings (nos. 11, 12, 13) and end-to-end anastomosis of the trachea were performed in 66 mongrel dogs, which were allocated to three groups (n = 22 in each). In the detached group, the trachea was entirely mobilized and isolated from the surrounding tissue for a length of 25 cartilage rings. In the wrapped group, omentopexy was added for the anastomosed site. In the control group, the same anastomosis was performed without omentopexy or detachment. The tracheal tissue blood flow was measured with a laser Doppler flow meter at the anastomosed site, and the tensile strength was determined with a tensiometer.

RESULTS

All groups showed significant decreases in the blood flow on day 3, compared with the preoperative values, and increases stepwise from day 7 to day 21. On days 3, 7, and 14 the tissue blood flow was significantly (p < 0.01) higher in the wrapped group than in the detached group, although on day 21 it did not differ significantly among the three groups. The tensile strengths of the cartilaginous and membranous portions were significantly (p < 0.05) higher in the wrapped and control groups than in the detached group. On day 21, no significant intergroup differences were observed for this parameter. In the wrapped group and in the control group, the capillary network at the anastomosed site was well developed on day 7, and the tracheal mucosal epithelium was well regenerated on day 21 without granulation formation.

CONCLUSIONS

This study showed that omentopexy at the anastomosed site of an extensively detached trachea provided adequate wound healing caused by rapid recovery of the tissue blood flow.